Methods of modifying the porous surface of implants

Abstract

Methods are provided for modifying a porous surface of an implantable medical device by subjecting the porous surface to a modified micro-arc oxidation process to improve the ability of the medical device to resist microbial growth, to improve the ability of the medical device to adsorb a bioactive agent or a therapeutic agent, and to improve tissue in-growth and tissue on-growth of the implantable medical device.

What is claimed is: 
     
       1. A method of manufacturing one or more medical devices, comprising:
 securing an electrode to each one of a plurality of metallic substrates in a first electrolyte solution; 
 providing a cathode in the first electrolyte solution; 
 sequentially applying a voltage to each one of the plurality of metallic substrates to form a plurality of micro-pores on the plurality of metallic substrates by micro-arc oxidation, 
 wherein sequentially applying the voltage includes using a controller to control the voltage and a timing of application of the voltage to each one of the plurality of metallic substrates; and 
 depositing a therapeutic agent on the plurality of micro-pores on the plurality of metallic substrates, 
 wherein depositing the therapeutic agent comprises electrophoretic deposition or electrodeposition of the therapeutic agent in a second electrolyte solution. 
 
     
     
       2. The method of  claim 1 , wherein the controller comprises a switch, a circuit board, a relay, or a combination thereof. 
     
     
       3. The method of  claim 2 , further comprising circulating the first electrolyte solution through a temperature regulating device to maintain a temperature of the first electrolyte solution within a desired range and directing the first electrolyte solution toward the plurality of metallic substrates to remove heat and gases from the plurality of metallic substrates while applying the voltage. 
     
     
       4. The method of  claim 1 , wherein the plurality of metallic substrates includes a porous oxide layer that comprises an anode of an electrolytic cell when immersed in the first electrolyte solution. 
     
     
       5. The method of  claim 4 , further comprising:
 oxidizing the porous oxide layer to form the plurality of micro-pores wherein the plurality of micro-pores is in the porous oxide layer of the plurality of metallic substrates; and 
 wherein depositing the therapeutic agent comprises depositing the therapeutic agent on the porous oxide layer having the plurality of micro-pores. 
 
     
     
       6. The method of  claim 5 , wherein depositing the therapeutic agent on the porous oxide layer having the plurality of micro-pores includes pulsed electrophoretic or pulsed electrodeposition. 
     
     
       7. The method of  claim 5 , wherein the plurality of metallic substrates further includes a non-porous surface and the method comprises depositing the therapeutic agent on the plurality of metallic substrates including performing a second deposition process to deposit the therapeutic agent on the non-porous surface. 
     
     
       8. The method of  claim 7 , wherein depositing the therapeutic agent on the porous oxide layer comprises applying a first voltage to the porous oxide layer and the second deposition process comprises applying a second voltage to the non-porous surface, wherein the first voltage is different from the second voltage. 
     
     
       9. The method of  claim 1 , further comprising manipulating the voltage or manipulating a current to control deposition of the therapeutic agent on at least one of a non-porous surface and a porous surface of the plurality of metallic substrates. 
     
     
       10. The method of  claim 1 , wherein the current is manipulated by decreasing or increasing a surface area of the cathode that is exposed to the second electrolyte solution. 
     
     
       11. The method of  claim 9 , wherein manipulating the voltage includes switching the cathode that is exposed to the second electrolyte solution on and off at least twice. 
     
     
       12. The method of  claim 1 , wherein the first electrolyte solution has a temperature of 10° C. or less. 
     
     
       13. The method of  claim 1 , wherein the first electrolyte solution differs from the second electrolyte solution by at least one of a composition or concentration. 
     
     
       14. A method of manufacturing one or more medical devices, comprising:
 securing an electrode to each one of a plurality of metallic substrates in an electrolyte solution; 
 providing a cathode in the electrolyte solution; 
 sequentially applying a voltage to each one of the plurality of metallic substrates, wherein sequentially applying the voltage includes using a controller to control the voltage and a timing of application of the voltage to each one of the plurality of metallic substrates, wherein the plurality of metallic substrates includes a porous oxide layer that comprises an anode of an electrolytic cell; 
 oxidizing the porous oxide layer to form a plurality of micro-pores in the porous oxide layer by micro-arc oxidation; and 
 depositing a therapeutic agent on the porous oxide layer having the micro-pores, wherein depositing the therapeutic agent on the porous oxide layer having the micro-pores includes switching the voltage to the cathode on and off at least twice, 
 wherein the plurality of metallic substrates includes a non-porous surface and further comprising depositing the therapeutic agent on the porous oxide layer includes performing a second deposition process to deposit the therapeutic agent on the non-porous surface. 
 
     
     
       15. The method of  claim 14 , wherein the depositing the therapeutic agent on the porous oxide layer comprises applying a first voltage to the porous oxide layer and the second deposition process comprises applying a second voltage to the non-porous surface, wherein the first voltage is different from the second voltage. 
     
     
       16. The method of  claim 14 , further comprising manipulating the voltage to the cathode or manipulating a current to control a deposit of a therapeutic agent on at least one of a non-porous surface and a porous surface of the plurality of metallic substrates. 
     
     
       17. The method of  claim 16 , wherein manipulating the voltage includes switching the cathode that is exposed to the electrolyte solution on and off at least twice. 
     
     
       18. The method of  claim 14 , wherein the controller comprises a switch, a circuit board, a relay, or a combination thereof. 
     
     
       19. The method of  claim 18 , further comprising circulating the electrolyte solution through a temperature regulating device to maintain a temperature of the electrolyte solution within a desired range and directing the electrolyte solution toward the plurality of metallic substrates to remove heat and gases from the plurality of metallic substrates while applying the voltage.